| Biography | |
|---|---|
 Dr. Jian Xie North China Electric Power University, China |
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| Title: Pseudo-boiling heat transfer mechanism of supercritical fluids and new non-dimensional supercritical-boiling-number SBO | |
| Abstract: Supercritical fluids are frequently applied in advanced power systems. To keep the safe and high-efficiency operation of these systems, it is important to accurately predicte thermal-hydraulic performces of supercritical fluids. However, the prediction is unsatisfactory based on classical single-phase assumption for supercritical fluid. Instead, pseudo-boiling concept is introduced here. Supercritical fluid is assumed to be heterogeneous structure, including a wall-attached gas-like layer and a liquid-like fluid in tube core. A new non-dimensional supercritical-boiling-number SBO is propesed, representing the bubble expansion induced momentum force against the inertia force. The thickness of wall-attached gas-like layer increases with rising SBO number. There exsits a critical SBO to trigger orifice contraction effect, yeilding wall temperatue peak and huge pressure drop. Thus, critical SBO determines the switch from normal heat transfer (NHT) to heat transfer deterioration (HTD). According to a large quantity of database, the critical SBO is identified as 5.126×10−4, 2.018×10−4, 1.653× 10−4 and 1.358×10−4 for CO2 , H2O, R134a and R22, respectively. New correlations of heat transfer coeffients and friction factors were also proposed based on SBO, which is suitable for both NHT and HTD, behaving much better prediction accuracy than those correlations in the literature. Our work provides a new perspective of pseudo-boiling heat transfer mechanism and supports the heterogeneous structure of supercritical fluids. | |
| Biography: Dr. Jian Xie is from North China Electric Power University. His research interest includes micro/nano heat transfer and multiphase flow, supercritical fluid heat transfer, low grade energy utilization. He published more than 30 papers on international journals. One paper theoretically solved a droplet dynamics problem proposed 20 years ago by France scientist Prof. David Quéré. He obtained 8 granted patents, amony which the pahse separation heat transfer exchanger won the excellent product award in China Hi-tech Fair. Due to these contubutions, Dr. Jian Xie was invited to be editorial board member of Journal of Thermal Science and performed 4 keynote/invited reports in international academic coferences. He also won the Chen Xuejun outstanding paper award for young scholars and IAAM award from international association of advanced materials. | |
